LED light sources (i.e., LED lamps or, more familiarly, LED “light bulbs”) provide an energy-efficient alternative to traditional types of light sources and may be used as a “drop-in” replacement in a lighting system in place of an incandescent, halogen, or florescent bulb. LED light sources typically require specialized circuitry to properly power the LED(s) within the light source, however, and this support circuitry must be compatible with the rest of the existing lighting system and circuitry (i.e., the circuitry that was formerly used or designed to power and control the incandescent, halogen, or florescent bulb). For example, different types of transformers and dimmer circuits may be already installed in a lighting system, and the LED light source must interface with these circuits.
A typical transformer may supply either a 12 V or 24 V nominal voltage in a lighting system. An LED light source receiving this voltage may behave differently when it receives a 12 V supply instead of a 24 V supply; for example, the LED may appear brighter when the light source receives the 24 V supply. This sort of variation in the light that a user of the LED light experiences is undesirable; ideally, the LED light source provides a consistent user experience that is independent of the type of circuitry used. Other circuits within the LED light source may also be affected; a bleeder circuit, for example, may overheat when exposed to a 24 V input.
The LED light source may attempt to detect the peak voltage level of the transformer, but this detection may be difficult because a dimmer circuit may vary the voltage before the LED circuit sees it. For example, it may be difficult to distinguish between (a) an incoming 12 V signal is being generated by a 12 V transformer and a dimmer circuit running at 0% dimming and (ii) a 24 V transformer and a dimmer circuit running at 50% dimming. A need therefore exists for a system and method for detecting the peak voltage of a transformer even if that voltage is modified by a dimmer circuit prior to detection.